As an apparatus for measuring the tension of a piston ring, in the past the following apparatus has been known (Japanese Patent Publication (A) No. 10-311763). A piston ring is attached to a ring holder which is then placed on a vibrating plate and vertical movement plate, a band-shaped member with one end which is fastened to a steel band holder is wound around an outer circumference of the piston ring, one end is fastened to a load cell, the load cell is made to move, the piston ring is squeezed until giving a ring gap in a state where as inserted at an inside circumference of the cylinder, then the tension is measured. At this time, the vertical movement plate gives an impact force to the piston ring to remove the large frictional force occurring between the band-shaped member and piston ring at the time of winding, while makes the vibrating plate vibrate to remove the small frictional force occurring between the band-shaped member and piston ring.